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Relativity/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim and Moby time-travel from the seventies into Tim's present-day bedroom. Moby is wearing a big-hair wig, and Tim is wearing Elton John glasses. There is a sheet of paper stuck to Moby's shoulder. MOBY: Beep. TIM: You said it, man. Nineteen seventy-seven was a really happening year. Tim removes his Elton John glasses. TIM: I'm just glad I got to see those bell-bottoms for myself. Hey, you got something there. Tim pulls the sheet of paper from Moby's shoulder. Tim reads from a typed letter. TIM: Dear Tim and Moby, I heard that if someone was on a spaceship traveling close to the speed of light, time would slow down. Is that true? From, Noah. Interesting question. First of all, no one can travel anywhere near the speed of light. The speed of light is the universe's ultimate speed limit, and it's about three hundred million meters per second. It would take an infinite amount of energy to make even the tiniest bit of matter go that fast, so you're asking about a hypothetical situation. An animation shows two planets in outer space, along with a sign. Text on the sign reads: Speed Limit, three hundred million meters per second. A spacecraft flies by. TIM: It is true, though, that some weird stuff would happen if you could. MOBY: Beep. TIM: Um, let's show them. Space trip. Tim and Moby are in a spaceship. They are sitting in pilot and copilot seats, looking out the front window at three of their friends. TIM: Okay, let's say you and I waved good-bye to our friends on Earth before taking a ride on a spaceship to a nearby star. Tim and Moby wave to their friends, who walk off. TIM: Ready? MOBY: Beep. TIM: I sure hope you know how to drive this thing. Tim pushes a button on the dash. TIM: Engage. The spaceship rumbles, and they blast off into space. TIM: Hey, Moby. Take it into overdrive. Moby activates a control, and the spaceship begins to go very fast. TIM: We'll need to go as close to the speed of light as you can get. The spaceship's speedometer nears three hundred million meters per second. Text reads: two point five years later, and the speedometer slows. TIM: Well, here we are at, uh, wait, what star is this, Moby? Tim and Moby pause near a yellow star. MOBY: Beep. TIM: Here we are at Minoui Relativa, and boy, is the view spectacular. Let's get a picture. Tim's hair is longer. Moby uses a camera to take a snapshot of the star. TIM: Right, then. I'm ready to go back. Are you? MOBY: Beep. Moby activates a control, and they head back to Earth at nearly the speed of light, according to the speedometer. Text reads: two point five years later. The speedometer slows again. TIM: Okay, get ready to be freaked out. The spaceship lands on a desert landscape. Tim has grown a beard and long, scraggly hair. The three friends they waved good-bye to turn up at the spaceship's front window. They are elderly. MOBY: Beep. Moby is distressed. TIM: Weird, isn't it? See, the faster you're going relative to a certain frame of reference, the slower time goes for you. Here on Earth, Cassie, Rita, and Gary experienced the passing of thirty-five years while we were gone. But because we were traveling at close to the speed of light, Moby and I only experienced the passage of five years. Animations compare Tim and Moby's three elderly friends with a still-young Tim. TIM: So, to answer Noah's question, yes, it really would happen like that if we could travel that fast. MOBY: Beep. TIM: Well, the effect has been demonstrated at slower speeds, too. Clocks on airplanes have been shown to tick a teeny bit slower than clocks on the ground. An image shows an airplane coming in for a landing at an airport. Images of clocks appear over the plane and the air traffic control tower. TIM: It all has to do with relativity. Relativity is a scientific theory that explains how things like motion, time, space, and gravity work. It was developed in the early twentieth century by a guy you might have heard of, Albert Einstein. An image shows Albert Einstein. TIM: Before Einstein, the universe's forces were best described by the English physicist Isaac Newton. An image shows Isaac Newton. He is holding an apple and frowning at it. TIM: Newton's explanations for things like gravity worked perfectly well most of the time. An animation shows an apple falling from a tree to the grass. TIM: But they fell short when trying to explain very large and very distant objects. An animation shows several types of galaxies drifting through deep space. TIM: So, being the genius that he was, Einstein came up with a better explanation, and that turned into his theories of relativity. MOBY: Beep. An image shows Einstein working on his theories at night. TIM: Yeah, theories. There are actually two types of relativity, and they describe different things about the universe. The first one, special relativity, deals with the relationships between speed, time, and distance. To start with, special relativity says that light always travels at the same speed, the speed of light. Moby flips on a flashlight. Text in the flashlight beam reads: speed of light equals two hundred ninety-nine million, seven hundred ninety-two thousand, four hundred fifty-eight meters per second. TIM: But also, Einstein found that it's impossible to tell whether you're moving unless you can determine that you're moving relative to some other object. An animation shows a little green alien in a flying saucer. It moves past a planet. TIM: Because of that, time and distance can't be absolute. They can change, like we saw with the spaceship example. MOBY: Beep. TIM: Right. Special relativity also gave us probably the most famous equation of all time, E equals mc squared. In a nutshell, it means that matter and energy are the same thing, which is one of the most important and far-reaching ideas ever thought up. You can learn more about it in our other features. An animation shows waves and particles as well as the equation E equals mc squared. TIM: Anyway, the other type of relativity is called general relativity. When Einstein wrote about this, he was trying to describe the force of gravity. One big discovery of his was that gravity is equivalent to acceleration. An animation shows the Moon revolving around Earth and both revolving around the Sun. TIM: So the force you feel when you're lifted in an elevator feels the same as the force of gravity pushing you down. Tim stands in an elevator that is going up very quickly. The acceleration pulls at him. He puts effort into remaining on his feet. TIM: But more importantly, general relativity says that gravity can affect time and space. See, space and time are interrelated. They can be thought of as a four-dimensional thing called spacetime. In general relativity, massive objects bend the fabric of spacetime around them. An animation uses a grid to illustrate Tim's explanation. A planet is placed on the grid, and the grid bends around the planet. TIM: This idea led physicists to start understanding things like the existence of black holes and the origin and fate of the universe. MOBY: Beep. An image shows a black hole in space. TIM: Yeah, it'll blow your mind if you think about it for a while. MOBY: Beep. Moby taps his seventies big-hair wig. TIM: Take that thing off. You look ridiculous. MOBY: Beep. Moby gestures that Tim's beard looks ridiculous. MOBY: Beep. Moby smiles. TIM: Oh, right. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts